1. Field of Invention
The present invention relates to a high and low temperature resistant floating ball valve for heating ventilation air conditioning pipelines in the filed of heating ventilation air conditioning temperature control.
2. Related Art
A large number of modernized office buildings and malls have been continuously set up with the development of urbanization of the country. Central air conditioning systems on the one hand provide comfortable environment required for people's working and living demands, and on the other hand take great energy consumption. According to the relevant statistics, the energy consumption of the air conditioning system takes up 50-60% of the total energy consumption of the buildings, takes up one third of the total electric load of the whole city during the peak load in summer, which case is still getting more and more serious. It is mentioned in the Guideline for the Eleventh Five-Year Plan that a society of resources-saving and environment-friendly buildings should be established in the country. It is said that the GDP unit consumption shall be decreased by 20% as of 2010. The energy saving technology for central air conditioners is one of ten energy saving engineering technologies proposed by the National Committee of Development and Reform.
At present, the central air conditioning systems reconfigure the energy saving of the transportation system of the air-conditioners by employing variable flow control, wind control and large temperature differences, for the purpose of reducing the energy consumption of the air conditioners. The electric control valve is the core operating part of the central air conditioning systems of variable flow control, which could automatically adjust the valve opening on the basis of the changes of the stability control signals of the target areas, so as to change the water flow rates and finally accomplish precise temperature control. The waterways required to be adjusted via electric valves include, throughout the whole central air conditioning systems, refrigerant loops, fan coils and new fan groups at the end of cool (hot) medium water, cooling water control loops, heat exchange control loops, steam control loops, and so on. The electric control valves do not display a good performance, which not only degrades the temperature control precision and negative affects the comforts of people, but also decrease the stability of the systems themselves. The electric control valves currently used have numerous disadvantages such as poor reliability, poor sealing property, high tendency to be damaged, high tendency in running, emitting, dropping and leaking, poor control precision, high noises in operation as well as high costs for maintenance and replacement. The energy saving effect of the central air conditioning systems is seriously influenced attributing to the aforementioned disadvantages.
The conventional valves generally include normal temperature valves and could not be employed in high temperature pipelines, for example pipelines in steam systems. The electric floating ball valves are thus proposed to address said problem, which are made of steel materials and could achieve the purpose of stably opening and closing in the pipeline systems of high temperature mediums.
In the conventional electric floating ball valves, the parts for controlling the action of the valve cores are implemented with the electric actuators including motors and transmission gear units. The motors are connected with the input ends of the transmission gear units, and the output ends of the transmission gear units are connected with the valve stems of the electric floating ball valves. The valve stems are driven to rotate by the motors through the transmission gear units so at to open and close the valves, when the valves are to be opened or closed.
However, as the electric floating ball valves are used in high temperature pipeline systems, the heat would be quickly transferred from the valve stems to the transmission gear units and motors. It is obvious that the transmission power of the transmission gear units is influenced by the over high temperature, and the use life of the motors would be influenced by the over high temperature at the motors. The other existing electric valves also have similar pitfalls.